1. Field of the Invention
The invention relates to a control system for cutting machines and, more particularly, to servo control systems for work and feed cutting machines.
2. Description of the Prior Art
In U.S. Pat. No. 3,789,279, issued Jan. 29, 1974, assigned to the assignee of the present invention a work and feed control system for cutting machines is described in connection with a concrete cutting system. Briefly, therein a cutting motor drives a blade through a sheet of concrete. The cutting motor is mounted on a carriage which rolls or slides on a rail. A feed motor moves the carriage along the rail, so as to drive the blade into the concrete. A control system is provided to control the load on the cutting motor for optimum cutting and automatically corrects the cutting rate as conditions change. Control knobs permit an operator to set the desired load level. When the cutting motor load level exceeds a predetermined threshold load level the direction of rotation of the feed motor is reversed at full speed, and thereafter is switched back to the forward direction at a relatively limited speed for a predetermined period, in order to avoid slamming the blade into the concrete.
Although the above-described system has been found to operate relatively satisfactorily it has been discovered that significant improvements may be made in the control system, so as to increase reliability and speed of operation. The present invention is directed to the novel improvements in such a system.